1. Field of the Invention
Subject matter of the invention is a device for use in the optical investigation of surfaces, especially microscope slides. The device contains a support to which a microscope slide holder is attached, and a holder that is attached to the support by means of at least one spacer unit. Attached to said holder is a line sensor in which numerous sensors are arranged in a row, and a lens system that forms an image of the microscope slide or a part of the microscope slide on the line sensor. The device also contains an illuminating device for illuminating the microscope slide and a drive for moving the holder basically vertically to the row of sensors in the line sensor by bending, tilting or pivoting the at least one spacer unit.
2. Description of the Related Art
In general, automated devices for investigating surfaces and microscope slides are based on a video system in which an image of the surface is projected onto a two-dimensional CCD array. The price of two-dimensional CCD arrays for use in video cameras has dropped dramatically in recent years. However, such CCD arrays that are common in the prior art are suitable for use in microscopic analysis only to a certain extent because they have a relatively small number of sensors and a relatively high rate of defective sensor elements. While the malfunction of individual pixels can be tolerated in inexpensive video cameras, these arrays are less suitable for use in microscopic analysis. CCD arrays with sufficiently high resolution and very low error rates are still very expensive and therefore not suitable for use in building a system for use in doctors offices and smaller laboratories.
An apparatus for counting microparticles is described in U.S. Pat. No. 4,550,417 in which an microscope slide is moved over a line sensor. In this method, the microscope slide is placed in a special holder that is moved by a linear drive. The linear drive shown in FIG. 4 comprises a synchronous motor that moves the sample carrier at a constant speed against the force of a return spring. To achieve the high level of precision necessary, the forces holding the sample carrier must be much greater than the friction forces produced when the sample carrier is moved. Accordingly, the system described here is equipped with a very strong motor and a correspondingly strong return spring. A further disadvantage of this apparatus is the fact that the sample is moved; the accelerative forces of the drive and shaking motions that are created when the sample carrier is transported cause the particles to be detected to move. This impairs the reliability of the counting and makes it difficult to identify and classify particles that are found using the sensor signals. Moreover, the apparatus described here uses a fixed light source to illuminate the sample carrier. This is a disadvantage, because the entire area that is observed must be illuminated homogeneously. As a result, the costly and energy-intensive method of illumination shown in FIG. 3 is required. To prevent the sample from being warmed by the light source, the light source is positioned away from the sample, and the light is directed by means of a reflecting mirror.